Accurate positioning of an unmanned mine vehicle using stationary obstacles

ABSTRACT

A method and system for stopping an unmanned mine vehicle in a predetermined position. The mine vehicle is driven at a low speed towards a physical. When the mine vehicle encounters the obstacle ( 7, 7   a   , 7   b ), a speed difference greater than a predetermined limit value is generated between the speed of the mine vehicle and the driving power transmission. The control system of the mine vehicle detects the exceeding of the limit value and stops the vehicle.

FIELD OF THE INVENTION

The invention relates to a method of stopping an unmanned mine vehiclein a predetermined position, the mine vehicle being controlled by meansof a control system comprising at least a first control unit in the minevehicle, a second control unit outside the mine vehicle and a datatransmission connection between said control units, and the methodcomprising: driving the mine vehicle, controlled by its control system,towards a predetermined position; and monitoring at least the speed ofthe mine vehicle and the speed of the driving power transmission of themine vehicle.

Further, the invention relates to a system for stopping an unmanned minevehicle in a predetermined position, the system comprising: at least acontrol unit including at least a first control unit in the minevehicle; a second control unit outside the mine vehicle and a datatransmission connection between said control units; and means formonitoring the speed of the mine vehicle and the speed of the drivingpower transmission of the mine vehicle.

The invention further relates to a system for stopping an unmanned minevehicle in a predetermined position, the system comprising a controlsystem including at least a control unit in the mine vehicle.

BACKGROUND OF THE INVENTION

Various unmanned mine vehicles are increasingly used in mines, whichvehicles are controlled by remote control from a monitoring room orwhich may operate independently in a mine according to their ownnavigation systems and an operating plan concerning the vehicles. Thereare situations where it is necessary to be able to stop an unmanned minevehicle accurately. For example transport vehicles and, on the otherhand, loading vehicles must be stopped in a certain position on theloading site in order for the loading of broken rock material to besuccessful. This imposes great requirements for the control systems ofunmanned mine vehicles. It is, however, very difficult and expensive toconstruct control systems capable of extremely accurate stopping indemanding mine conditions. Furthermore, the control system easilybecomes complex and sensitive to failures.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a novel and an improvedarrangement for stopping an unmanned mine vehicle very accurately in apredetermined position.

A method according to the invention is characterized by driving the minevehicle at a speed significantly lower than the normal driving speedagainst at least one physical obstacle that is arranged in apredetermined position; and stopping the mine vehicle when the ratio ofthe speed of the driving power transmission to the speed of the minevehicle exceeds a predetermined limit value.

A system according to the invention is characterized in that the systemfurther comprises: at least one physical obstacle arranged in apredetermined position, against which the mine vehicle is arranged to bedriven; and means for stopping the mine vehicle when the ratio of thespeed of the driving power transmission of the mine vehicle to the speedof the vehicle exceeds a predetermined limit value.

A second system according to the invention is characterized in that thesystem further comprises: at least one physical obstacle arranged in apredetermined position, against which the mine vehicle is arranged to bedriven; means for determining the tractive resistance of the minevehicle when said obstacle is approached; and further, means forstopping the mine vehicle when the tractive resistance exceeds apredetermined limit value.

An essential idea of the invention is that an unmanned mine vehicle isdriven at a speed significantly lower than the normal driving speedtowards a physical obstacle that is positioned in a predeterminedposition. At the same time, the speed of the mine vehicle and the speedtransmitted from the driving power transmission of the vehicle aremonitored. When the mine vehicle encounters the obstacle, the obstacleresists the proceeding of the vehicle. As a result of the tractiveresistance, a speed difference is generated between the speed of themine vehicle and the speed of the driving power transmission. In thecontrol system of the mine vehicle, a limit value has been set for thespeed difference. When the control system detects that the limit valuehas been exceeded, it concludes that the mine vehicle has been drivenagainst the obstacle, after which it stops the vehicle.

An advantage of the invention is that the stopping system is rathersimple to implement. Further, the system is reliable, because stoppingis based on using a physical obstacle. The location of the obstacledetermines the precise stopping point, whereby the locationdetermination does not necessarily require complex positioning systemsor heavy processing of the location information. Furthermore, nofailure-sensitive proximity sensors or other corresponding componentsare needed in the system. Owing to its simplicity, the system accordingto the invention is also inexpensive. Also, the system according to theinvention may be applied relatively easily to present unmanned minesalready in use.

The essential idea of an embodiment of the invention is that the speedof the traction wheels of the vehicle is monitored, and if the speeddifference between the speed of at least one traction wheel and thespeed of the vehicle exceeds a predetermined limit, the mine vehicle isconcluded to be against the obstacle. The speed of the vehicle can bedetermined by monitoring the speed of the wheels rolling freely.Monitoring the wheel speeds is relatively simple.

The essential idea of an embodiment of the invention is that theobstacle is approached at a decelerating speed. Thus, when the vehiclecollides with the obstacle, no damage is caused for the vehicle orobstacle.

The essential idea of an embodiment of the invention is that at leastone wheel of the mine vehicle is driven against the obstacle.

The essential idea of an embodiment of the invention is that the frameof the mine vehicle is driven against the obstacle.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be explained in more detail in the attached drawings,of which

FIG. 1 shows schematically a side view of an unmanned mine vehicleaccording to the invention, stopped in a manner according to theinvention in a predetermined position;

FIG. 2 shows schematically a top view of a loading site where stoppingaccording to the invention is applied;

FIG. 3 shows schematically a side view of an embodiment of the solutionaccording to the invention; and

FIG. 4 shows schematically a second embodiment of the system accordingto the invention.

For the sake of clarity, the invention is shown simplified in thefigures. Similar parts are denoted with the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an unmanned mine vehicle 1, in this case a loading vehicle1 a, which is a kind of wheel loader, there being a bucket 2 in itsfront part, with which crushed material can be transported from oneplace to another and loaded to other transport means, such as conveyorsand transport vehicles 1 b. The mine vehicle 1 comprises a first controlunit 3, which is in connection with an outside second control unit 4 bymeans of a data transmission connection 5. The second control unit 4 maybe arranged for instance in a monitoring room 6 outside the mine. Boththe first control unit 3 and the second control unit 4 may be computers,in which computer programs intended for controlling the mine vehicle canbe run. The data transmission connection 5 between the control units 3and 4 may be either wired or wireless.

In FIG. 1, the loading vehicle 1 a is stopped against an obstacle 7, atan appropriate distance from a pass chute 8, in which the bucket 2 ofthe loading vehicle 1 a is intended to be emptied. The obstacle 7 ispositioned at a distance L₁ from the chute 8, whereby the rock material9 can be dropped from the bucket 2 directly into the chute 8 or, forinstance, to a conveyor. The distance L₁ is mainly affected by thedimension of the loading vehicle 1 a itself. The height H of theobstacle 7 is dimensioned in such a way that the bucket 2 can be guidedover it without difficulties. When the vehicle 1 a has collided with theobstacle 7 in the driving direction A, its speed is substantially zero.The traction wheels 10 of the vehicle 1 a, by contrast, continue to rollat the original speed at least for a moment. Subsequently, either powertransmission 20 compensates for the generated speed difference or thewheels begin to slip on a surface 11 where the vehicle is driven. Thestopping system according to the invention detects that the speeddifference generated between the vehicle frame 12 and the wheels 10 hasexceeded a predetermined limit value, and it stops the vehicle. Thesystem may also automatically put the driving gear into neutral gear andengage the brakes. The mine vehicle 1 exits this position only after ithas received instructions for it from the control unit 3.

A limit value for the allowed speed difference may be set in the controlsystem of the mine vehicle 1. The allowed speed difference of the speedof the driving power transmission 20, such as a gear system, tractionwheels 10 and other components to be monitored, in relation to the speedof the vehicle may be determined in such a way that changes in speed dueto the quality of the surface 11 or steering of the vehicle 1 are notinterpreted as stopping against the obstacle 7. It is possible that thespeed monitoring is not switched on before the mine vehicle 1 begins toapproach the obstacle.

Further, the control system may be arranged to monitor the rotationspeed of the motor 30 of the vehicle 1. When the mine vehicle 1 isdriven at a particular gear, usually at the lowest gear, against theobstacle 7, the tractive resistance grows, due to which the anti-slipregulation of the power transmission 20 of the mine vehicle 1 begins tolimit the torque to be transmitted to the wheels. For example a torqueconverter, a clutch or a corresponding component belonging to the powertransmission may be arranged to slip. When the loading thus decreases,the rotation speed of the motor 30 may increase. The control systemdetects the increase in the rotation speed and stops the mine vehicle 1.

The stopping system according to the invention may be a computer programthat can be executed in a computer belonging to the control system ofthe mine vehicle. The computer program may be stored in the memory ofthe control system or it may be loaded there from a memory device or adata network.

FIG. 2 shows a loading site 13, where the transport vehicle 1 b, i.e.what is called a dumper, is stopped according to the invention in apredetermined position to wait for loading. The loading site 13 has afirst obstacle 7 a, against which the transport vehicle 1 b has beendriven in direction A′. Further, a second obstacle 7 b has been arrangedon the loading site 13, towards which the loading vehicle 1 a is drivenin direction A″, i.e. in the transverse direction relative to thetransport vehicle 1 b. In this way, the loading vehicle 1 a and thetransport vehicle 1 b can be stopped accurately in a predeterminedposition relative to each other, whereby the bucket 2 of the loadingvehicle 1 a can be emptied accurately to the platform 14 of thetransport vehicle 1 b. An advantage of the system is that it does notrequire complex means for determining the locations of the vehicles. Themine vehicles 1 are stopped in their longitudinal directions, either bydriving forwards or alternatively by backing up. The control systemattends to the vehicles being stopped correctly in the lateraldirection.

In FIG. 3, the wheel 10 of the mine vehicle 1 is driven in the way shownby a broken line against the physical obstacle 7. In this case, theobstacle 7 is dimensioned so low that the platform 14, the bucket 2 orthe frame 12 of the mine vehicle 1 does not hit it. On the other hand,the height of the obstacle 7 must be such that the wheel 10 cannot riseover it. The solid-rubber or inflated wheel 10 may yield somewhat whenit hits the obstacle 7, and the wheel 10 may thus dampen the collisionforces to some extent. Further, since the location of the obstacle isknown to the control system of the mine vehicle 1, the vehicle 1 canapproach the obstacle 7 at a decelerating speed. The closer to theobstacle 7 the vehicle 1 is, the lower the speed of the vehicle 1. Thespeed can be lowered continuously or, alternatively, step by step.

FIG. 3 further shows an arrangement where a member 15 monitoring thespeed of the mine vehicle 1 and, correspondingly, one or more members 16monitoring the speed of the traction wheels 10 of the vehicle transmitmeasurement data to the first control unit 3, which calculates, on thebasis of the measurement data, the speed differences between the vehicle1 and the wheels 10 and compares them to the limit values that have beengiven to the control unit 3 beforehand. Alternatively, the speed of thevehicle and the speed transmitted via components of the driving powertransmission 20, such as the gear system, may be monitored. Further, therotation speed of the vehicle motor may be measured, and the speed ofthe driving power transmission 20 may be found out on the basis of thedriving gear used. The speed of the vehicle 1 can be determined forinstance by measuring the speed of the wheels rolling freely. Further,suitable measuring devices, such as laser and radar, may be used. It isalso possible to determine the speed of the vehicle 1 by comparing thevideo image of the shape of the mine surface, transmitted from thevehicle 1, with another video image that is stored in the memory of thecontrol system. It can be mentioned that the stopping system may utilizesensors of the anti-slip regulation and other possible devices relatedto measuring the speed.

In FIG. 4, the frame 12 of the mine vehicle has been driven against theobstacle 7. As seen from FIG. 4, the obstacle 7 may be a fixed wall orborder arranged on the floor 11 of the mine and encased in concrete, forexample. As seen from the figure, the mine vehicle 1 may comprise abumper 17 provided with a damper 18. Owing to the damper 18, the contactbetween the mine vehicle 1 and the obstacle 7 may be softer.Alternatively, the obstacle 7 may be provided with an appropriatedamper.

The obstacle 7 may be formed fixedly in a desired place, for instance byencasing in concrete, or alternatively, the obstacle may be a movablestructure which remains in place due to its own mass, or the obstacle 7may be provided with suitable fixing members that stand the collisionforces generated in the stopping and prevent the obstacle 7 from movingin the driving direction A of the mine vehicle 1. It is also possible toarrange the obstacle 7 in such a way that it can be moved by remotecontrol. Thus, the obstacle 7 may be lowered with a hydraulic cylinderso that it is not in the way of the transport vehicle 1 b when theloading is completed. Thus, the vehicle can be driven from the loadingsite to the discharge site without having to back up.

Further, the system according to the invention can be used for drivingan unmanned mine vehicle to a reference point. Obstacles of the typedescribed above may be formed for an unmanned mine, the locations ofwhich are known to the control system. When the mine vehicle is drivenagainst an obstacle, the accurate location of the mine vehicle can beupdated for the control system. Further, the method according to theinvention can be utilized for stopping a mine vehicle in a predeterminedposition in a mine for maintenance and battery charge.

The tractive resistance of a mine vehicle can also be measured in waysother than the ones described above. One option is to measure the torquetransmitted by the power transmission. A second option is to monitorclutches belonging to the anti-slip regulation and other components ofthe power transmission. Yet a third option is to provide the bumper of amine vehicle or the like with force sensors which, when approaching theobstacle, detect that the tractive resistance has increased.

The drawings and the related description are only intended to illustratethe idea of the invention. The details of the invention may vary withinthe claims.

1. A method of stopping an unmanned mine vehicle in a predeterminedposition, the mine vehicle being controlled by means of a control systemcomprising at least a first control unit in the mine vehicle, a secondcontrol unit outside the mine vehicle and a data transmission connectionbetween said control units, and the method comprising: driving the minevehicle, controlled by said control system, towards a predeterminedposition; monitoring at least a speed of the mine vehicle and a speed ofthe driving power transmission of the mine vehicle, driving the minevehicle at a speed significantly lower than a normal driving speed anddriving intentionally against at least one physical stationary obstaclethat is arranged in a predetermined position wherein the mine vehiclecollides with the obstacle; and stopping the driving power of the minevehicle when a ratio of the speed of the driving power transmission tothe speed of the mine vehicle exceeds a predetermined limit value as aresult of a tractive resistance caused by the obstacle resisting theproceeding of the mine vehicle after collision.
 2. A method according toclaim 1, comprising monitoring the speed of traction wheels; andstopping the mine vehicle when the ratio of the speed of at least onetraction wheel to the speed of the mine vehicle exceeds a predeterminedlimit value.
 3. A method according to claim 1, comprising monitoring arotation speed of a motor of the mine vehicle when the vehicle is drivenat a given gear of a driving power transmission against the obstacle;and stopping the mine vehicle when the ratio of the rotation speed ofthe motor to the speed of the mine vehicle exceeds a limit value definedaccording to a gear used.
 4. A method according to claim 1, comprisingdriving the mine vehicle at a decelerating speed against the obstacle.5. A method according to claim 1, comprising driving at least one wheelof the mine vehicle against the obstacle.
 6. A method according to claim1, comprising driving the frame of the mine vehicle against theobstacle.
 7. A system for stopping an unmanned mine vehicle in apredetermined position, the system comprising: a control unit includingat least a first control unit in the mine vehicle; a second control unitoutside the mine vehicle; a data transmission connection between saidcontrol units; means for monitoring a speed of the mine vehicle and aspeed of a driving power transmission of the mine vehicle, at least onephysical stationary obstacle arranged in a predetermined position,against which the mine vehicle is arranged to be driven intentionallyand to collide with the obstacle; and means for stopping a driving powerof the mine vehicle when a ratio of the speed of the driving powertransmission of the mine vehicle to a speed of the vehicle exceeds apredetermined limit value as a result of a tractive resistance caused bythe obstacle resisting the proceeding of the mine vehicle after thecollision.
 8. A system according to claim 7, wherein the systemcomprises members for monitoring speed of the traction wheels of thevehicle and for determining a speed of the driving power transmission.9. A system according to claim 7, wherein the system comprises means formonitoring a rotation speed of the motor of the mine vehicle; and thesystem is arranged to stop the mine vehicle when a ratio of the rotationspeed of the motor to the speed of the mine vehicle exceeds a limitvalue defined according to a gear used.
 10. A system for stopping anunmanned mine vehicle in a predetermined position, the systemcomprising: a control system including at least a control unit in themine vehicle; at least one physical stationary obstacle arranged in apredetermined position, against which the mine vehicle is arranged to bedriven intentionally and to collide with the obstacle; means fordetermining tractive resistance of the mine vehicle when said obstacleis approached; and means for stopping a driving power of the minevehicle when the tractive resistance exceeds a predetermined limit valueafter the collision against the obstacle.
 11. A system according toclaim 10, wherein the system comprises means for determining a speed ofthe mine vehicle; the system comprises means for monitoring a rotationspeed of a motor of the mine vehicle; and the system is arranged to stopthe mine vehicle when a ratio of the rotation speed of the motor to thespeed of the mine vehicle exceeds a limit value defined according to agear used.
 12. A system according to claim 10, wherein the systemcomprises members for monitoring speed of the traction wheels of thevehicle and for determining a speed of the driving power transmission.13. A system according to claim 7 wherein the system comprises at leastone physical stationary reference obstacle arranged in a location knownto the control system, and when the mine vehicle is driven against thereference obstacle in the known location, the location of the minevehicle is updated for the control system.
 14. A system according toclaim 7 wherein the mine vehicle is a wheel loader comprising a bucketfor transporting broken rock material from a loading place to anunloading place, the physical stationary obstacle is arranged in apredetermined distance from the unloading place, and the wheel loader isdriven against the physical stationary obstacle and bucket of the wheelloader is emptied.
 15. A system according to claim 7, wherein the systemcomprises at least one loading vehicle provided with a bucket and atleast one transport vehicle provided with a platform, the systemcomprises a loading site wherein the loading vehicle is arranged to loadbroken rock material to the transport vehicle, the loading sitecomprises a first physical stationary obstacle against which thetransport vehicle is driven and a second physical obstacle against whichthe loading vehicle is driven, and the positions of the transportvehicle and the loading vehicle relative to each other is determined bythe relative positions of the first and second physical stationaryobstacles.